Question

An isosceles triangle has base angles that each measure 69o. Which equation can be used to find x, the measure of the third angle?

a
138 + x = 180
b
69 + x = 180
c
138 + 2x = 180
d
2x + 69 = 180

Answer 1

a. 138 + x = 180

Explanation:

Because the angles given are 69+69

which equal 138

and x being the missing angle

finally the total of all angles in a triangle = 180